Recently, a case that a user is using an IP sharing device so that many clients can use a network using only one authorized IP address at the same time are generated frequently. Further, there is a trend that many companies and enterprises which configures NAT are increasing bit by bit. Thus, there is a problem that a network traffic, necessity of new facilities, and investment money are increased due to the above trend.
But, such a problem can be solved by counting accurately the number of actual clients who use a network for each line, but when the actual IP addresses of the users of NAT or IP address sharing devices pass through NAP or the IP address sharing devices, they are changed into the authorized IP addresses and it is not possible to grasp the number of the actual clients of an user.
In order to solve this problem, an additional application (Active X, Agent) informing a user's IP address or the number of terminals in an inner network must be mounted. But, after a user recognizes the mounting/operation of this application, he may not execute this application.